Silicon carbide is expected as a material for next generation semiconductor devices. Compared to silicon, silicon carbide has superior physical properties such as a band gap of approximately 3 times, a breakdown field strength of approximately 10 times, and a thermal conductivity of approximately 3 times. By utilizing these physical properties, it is possible to realize a semiconductor device capable of operating with low loss and high temperature.
As a structure for reducing the on-resistance of a metal oxide semiconductor field effect transistor (MOSFET) using silicon carbide, there is a trench gate type MOSFET in which a gate electrode is provided in a trench. In a trench gate type MOSFET, the on-resistance is reduced, since the channel density per unit area is increased. In a trench gate type MOSFET, it is further expected to realize a structure for reducing the on-resistance.